Focused ion beam tomography of WC-Co cemented carbides

Abstract

The microstructure of three different grades of WC-Co cemented carbides has been reconstructed in three dimensions after sequential images obtained by focused ion beam.The three-dimensional microstructual parameters are compared against the well-know two-dimensional parameters of grain size, phase percentages and mean free path. Results show good agreement with the exception of individual grain recognition, which could not be univocally segmented. In the case of mean free path, the three-dimensional image depicts a more realistic image of the metal interconnections in the composite.For the grade with coarser grain size, the obtained tomography is translated in a finite element modelling mesh, and elastic residual stresses are estimated from sintering to room temperature. Calculated thermal stresses agree with experimental results and show significant local variations in their value due to the complex microstructure of cemented carbides.

Influence of specimen size and microstructure on uniaxial compression of WC-Co micropillars

“…WC-Co cemented carbides (usually referred to as hardmetals) are materials used widely in the tooling industry due to their elevated hardness, strength, elastic modulus, rigidity, and wear resistance. The outstanding mechanical and tribological response exhibited by them is a direct consequence of their microstructural assemblage: an interpenetrated network of two different phases (hard, brittle carbides and a soft, ductile metallic binder), with optimal interface properties [1][2][3][4][5]. In this regard, micromechanical models attempting to assess and predict performance of hardmetals have been developed regarding plastic deformation of the constrained metallic binder, microstructural aspects such as contiguity, shape and size of WC grains, and even anisotropy of the constitutive phases [6][7][8].…”

“…independent of bulk-like or micropillar consideration) of cemented carbides should be recalled based on synergic interaction of deformation phenomena taking place within the constitutive phases. As it has been well-established in several studies involving modeling actions[5,[36][37][38], regions neighboring geometry irregularities of particles as well as the wide range of thermal M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT residual stresses for WC (compressive in average but tensile in specific regions) due to particle shape and microstructure itself, may result in plasticity being developed at effective stresses lower than those measured in isolated WC single crystals. Considering that elastic modulus values found in this study are within the ranges of what is expected for WC-Co alloys with similar microstructures to those studied here, and that plasticity events evidenced may be rationalized on the basis of: mechanical response reported for unconstrained and (variably) constrained binder, WC particles, and regions containing WC/WC and WC/Co interfaces; it may be stated that combination of an accurate selection of the REV and uniaxial compression of micropillars (following testing parameters proposed) allows reliable assessment of the mechanical properties of WC-Co cemented carbides.…”

Assessment of mechanical properties at microstructural length scale of Ti(C,N)–FeNi ceramic-metal composites by means of massive nanoindentation and statistical analysis

“…Cemented carbides are a group of ceramic-metal composite materials with exceptional combinations of hardness, strength and toughness together with unique wear and abrasion resistance [1,2]. Main reasons behind it are the wide range of microstructural assemblages available for these composites, all of them consisting of interpenetrating networks of two phases with completely different properties: hard/brittle ceramic particles and soft/ductile metallic binder [3][4][5]. Among these materials, WC-Co alloys, also referred to as hardmetals, are one of the most successful "tailor-made" composites.…”

Corrosion-Induced Damage and Residual Strength of WC-Co,Ni Cemented Carbides: Influence of Microstructure and Corrosion Medium

“…The main reason behind this is the unique combination of hardness, toughness, and wear resistance they exhibit. It results from their two-phase interpenetrated network as well as the intrinsic properties of the ceramic particles and the metallic binder [1][2][3][4][5]. Many of the referred applications often imply exposure of cemented carbides tools and components to chemically aggressive media including a large variety of corrosive environments, such as lubricants, chemical and petrochemical products, as well as mine-and sea-water (e.g., References [6][7][8][9]).…”